Ruby

• vm_trace.c (rb_suppress_tracing): bugfix for vm->trace_running
  counter. And if tracing is already true, vm_trace_running ops is
  skipped to control overflow.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e